Rotor structure

ABSTRACT

A regenerative heat exchanger comprising a rotor having a support structure disposed intermediate the heat exchange surface with the latter being supported therefrom in cantilever fashion and including means compensating for thermal expansion and contraction of the surface independent of the support structure.

United States Patent 1191 Eisenstein Aug. 20, 1974 ROTOR STRUCTURE 3,229,753 1/1966 Gram, Jr. et al 165 7 [75] Inventor: Albert Eisenstein, Akron, Ohio FOREIGN PATENTS OR APPLICATIONS 73 Assignee; The Babcock & wflcox Company, 147,208' 7/1952 Australia l65/l0 New York, NY. P E Alb w D J rimary xaminerert avis, r. [22] filed: 1972 Attorney, Agent, or Firm-Joseph M. Maguire, Esq.; 211 App] 242,400 Robert J. Edwards, Esq.

52 US. c1. 165/10, 165/9 [57] ABSTRACT [51] Int. Cl. F28d 19/04 A regeneratlve heat exchanger compnsmg a rotor 581 Field of Search 165/8, 9, 10 ing a pp structure disposed intermediate the heat exchange surface with the latter being supported [56] Referen e Ci d therefrom in cantilever fashion and including means UNITED STATES PATENTS compensating for thermal expansion and contraction 2 432 198 12/1947 Karlsson et a] 165,10 of the surface independent of the support structure. 2:98l:52l 4/1961 Evans et a1. 165/7 1 Claim, 6 Drawing Figures PAIENIEMuczoxm FIG.2

PATENTEB 15201974 3.830.287 amaara FIG.5

RoToR STRUCTURE BACKGROUND OF THE INVENTION The present invention relates to rotary regenerative heat exchangers of the type which comprise a housing wherein there is provided a regenerative rotor having axial passageways for the flow of heat exchanging media therethrough and more particularly to an improvement in the rotor arrangement allowing for more uniform thermal expansion than has heretofore been possible.

In such heat exchange apparatus, the fluid to be heated and the heating fluid are preferably in counterflow relationship to one another with the inlet for the heating fluid and the outlet for the fluid to be heated being adjacent at one end of the heat exchanger, and the outlet for the heating fluid and the inlet for the fluid to be heated being adjacent at the opposite end thereof. The rotor end facing the heating fluid inlet lies in a relatively high temperature zone and is commonly referred to as the hot end whereas the end facing the heating fluid outlet lies in a relatively low temperature zone and is commonly referred to as the cold end. While the length of the axial passageways through the rotor may be comparatively small, the temperature gradient between the cold and hot ends of the rotor is appreciable and leads to non-uniform thermal expansion resulting in distortion or warping of the rotor structure to the extend that close tolerances cannot be maintained between the sealing surfaces separating the fluid passageways.

Heretofore, efforts have been made to overcome this difficulty by the development of flexible or otherwise adjustable sealing means to reduce the variable clearance space existing between the rotor surfaces confronting the housing and associated sector plates. However, any attempt to reduce the clearances between the confronting stationary and rotating elements of the heat exchanger must take into account the structural limitation which requires that clearances must be maintained which are sufficient to prevent excessive surface contact or jamming under the most adverse temperature conditions.

SUMMARY OF THE INVENTION The present invention is directed at a novel rotor construction allowing for exacting and close tolerances between confronting stationary and rotating elements of the heat exchanger by providing a rotor arrangement wherein the regenerative surface and related support structure achieve a more uniform thermal expansion. Accordingly, the present invention comprises a regenerative heat exchanger including a stationary housing formed with separate passageways and having inlet and outlet ducts connected to the end of these passageways to provide for separate flow of a fluid to be heated and a heating fluid therethrough. A rotor is disposed within the housing with portions lying in each of the passageways and sealing means are associated with the confronting stationary and rotating elements to eliminate or at least minimize the leakage of fluid between passageways. The rotor structure includes radially and transversally oriented coplanar strut members cooperating with one another to form one or more comparted sector-like support grids concentric with and attached to the hub portion of the heat exchanger. The heat exchange surface associated with the rotor comprises a plurality of bundles of spaced heat absorbent plates, wherein each bundle is shaped to have a transverse cross-section closely matching the contour of a corresponding compartment of the support grid. Where, as in the preferred embodiment, the support structure comprises two grids spaced along the longitudinal axis of the rotor shaft, the bundles of heat exchange surface cover substantially all of the outside radial end face of each of the grids. Each bundle appending from the grid in cantilever fashion and having one end rigidly connected and the opposite end thereof slidably connected to respectively adjacent transversally oriented strut members.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic end view of the regenerative heat exchanger embodying the invention.

FIG. 2 is a schematic sectional elevation of the regenerative heat exchanger embodying the invention.

FIG. 3 is a detail view of an installed bundle of heat exchange surface.

FIG. 4 is a fragmented sectional end view of the rotor showing heat exchange surface and the support structure therefor.

FIG. 5 is a sectional detail side view taken along line 5-5 of FIG. 4 and showing the heat exchange surface as installed on both radial end faces of the support structure.

FIG. 6 is a sectional detail plan view taken along line 6-6 of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGS. 1 and 2 of the drawings, there is schematically shown a regenerative heat exchanger 10 including a housing 12 having a hub portion 14 and enclosing a cylindrical rotor 16 rotatably associated with the hub portion 14. A drive motor and gear reduction box 18 is connected through the hub portion 14 to the rotor 16 to turn the latter slowly about its axis. The rotor 16 includes regenerative heat exchange surface in the form of closely spaced metallic plates which absorb heat, while slowly passing through a passageway 20, from hot gases entering the heat exchanger 10 through a duct 22 from a boiler or other source to be discharged, after passing over the heat exchange surface, through an outlet duct 24. As the rotor 16 turns slowly about its axis, the heated plates are moved into a passageway 26 where the heat is transferred to the air stream entering the heat exchanger 10 through a duct 28, the heated air is thereafter conveyed by a duct 30 to the boiler or other place of use.

Referring to FIGS. 3 through 6 of the drawings, there are shown a typical heat exchange surface bundle 32 and the rotor support structure 34 therefor. The bundle 32 comprises closely spaced metallic plates 36 held together by a rigid framework 37 including end sections 38 and 40 for connecting the bundle 32 to the support structure 34.

The support structure 34 extends outwardly from the shaft member 42 to the rim44 of rotor 16 and includes a plurality of interconnected radially and transversally oriented coplanar strut members 46A-B and 48, respectively. The strut members 46A-B and 48 cooperate with one another to form one or more comparted sector-shaped grids 50 concentric with the shaft member 42.

The support structure 34 of the preferred embodiment comprises two grids 50 spaced from one another along the longituginal axis of shaft member 42, however, it will be understood that the number of grids may vary in accordance with the structural requirements of the heat exchanger.

The grids 50 are structurally linked to one another through a series of axially oriented strut members 52 which are rigidly connected at their respective ends to adjacent radially oriented strut members 46A-B. The grids 50 are each in turn fixedly connected to the shaft member 42 through their respective fully-extending radial strut members 468 which have their hub ends rigidly connected to a shoulder portion 54 which may either be a ring plate or segment thereof rigidly connected to the shaft member 42. The grids 50 cooperate with the stationary housing 12 and the shaft member 42 to form an annular chamber 51 therebetween, and the latter is partitioned into a plurality of sectorial compartments 53 by axially oriented diaphragm members 56.

In accordance with the present invention, the heat exchange surface is disposed on the radial end face of the respective support grids 50 so as to substantially cover all of the exposed face of the grids. As aforementioned, the heat exchange surface comprises a plurality of bundles 32 of closely spaced plates 36 with each bundle 32 being shaped to closely match the contour of the sectonshaped compartments comprising the grids 50. The bundles 32 are mounted on the structure 34 in such manner as to compensate for the thermal expansion and contraction of the individual bundles 32 independent of the support structure 34.

The bundles 32 are supportingly connected to the respective grids 50 through the transverse strut members 48 which are provided with bolt holes 58 to accommodate locking bolts 60 that rigidly connect the bundles 32 to the grid 50. Each bundle 32 is provided with an end plate 38 extending in the direction of the rotor hub and an end plate 40 extending in the direction of the rotor circumference. The bundles 32 are aligned in sectorial fashion with the end plate 38 of one bundle overlapping the end plate 40 of the next adjacent bundle in the direction of the rotor hub. The end plates 40 are provided with bolt holes to accommodate the passage of locking bolts 60 and with the threaded studs 62 to receive the expansion slots 64 formed in the end plate 38 of the next adjacent bundle. The end plates 38 are scalloped whereever necessary to accommodate the bolts 60 and the reinforcing ribs 66, and a washer and nut arrangement 68 and 70, respectively, cooperates with each stud 62 to hold the bundle 32 onto the support structure 34 while allowing it to move freely in a radial direction to compensate for thermal expansion and contraction independent of the support grid.

The bundles 32 of heat exchange surface are of the hot end type 32A and the cold end type 328. The bundles 32A line the grid 50 which is nearest the gas inlet 22 and the air outlet 30 and form one end face of the rotor 16. The bundles 323 line the grid 50 which is nearest the gas outlet 24 and the air inlet 28 and form the opposite end face of the rotor 16. The transverse strut members 48 which support the bundles 32A-B are preferrably formed of angle plate whereas the radial and axial strut members 46A-B and 52 respectively, are formed of rectangularly cross-sectioned pipe. The hot and cold end radial seals 72 and 74, respectively are adjustably connected to seal carrier strips 76 which are in turn rigidly connected to the radial strut members 468.

The present invention provides a construction which places the support structure 34 in a zone where the temperature is relatively constant and intermediate of the hot end and cold end of the regenerative heat exchanger 10. Location in the hot end zone is undesirable from a heat stress standpoint, whereas, location in the cold end zone is undesirable because of low temperature corrosion. Thus, the radial, axial and transverse strut members which make-up the support structure 34 are not exposed to the deleterious effects of heat and corrosion, moreover, they are located in a zone of negligible thermal gradient and are therefore subjected only to minor differentials of thermal expansion between members.

Another feature of the present invention is the use of light gauge diaphragm plates 56 which readily deflect and therefore transmit only negligible load stresses to the shaft member 32.

Still another feature is the chamber 51 formed between the axially spaced grids 5 0 of the preferred embodiment and providing access means for the cleaning and installation of heat exchange bundles 32.

A further feature of the invention is directed at the arrangement wherein the bundles 32 cover substantially all of the outside radial end face of each grid 50 and are separately supported in cantilever fashion therefrom, thus the grids are protected by the heat exchange surface and each bundle 32 transmits its weight directly to the support structure 34 rather than through adjacent bundles. Moreover each bundle 32 includes the means for thermally expanding and contracting independent of the support structure 34.

While in accordance with provisions of the status there is illustrated and described herein a specific embodiment of the invention, those skilled in the art will understand that changes may be made in the form of the invention covered by the claims, and that certain features of the invention may sometimes be used to advantage without a corresponding use of the other features.

What is claimed is:

1. A regenerative heat exchanger comprising stationary structural members supporting the heat exchanger and having a hub portion, a shaft member rotatably supported in the hub portion, a cylindrical rotor concentrically fixed to the shaft member, the rotor including a plurality of sector-shaped heat exchange bundles and a support grid structure therefor, a stationary housing surrounding the rotor and means providing for the separate flow of a heating fluid and a fluid to be heated over the heat exchange bundles, each of the bundles being formed with a core of closely spaced plates including framework enclosing the core, and said framework having at least one bracket member connected to the grid structure wherein said bracket member is slotted for permitting expansion and contraction of the heat exchange bundle independent of said grid structure.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION I Patent No. w Dated Augus 97 Inventor(S) Albert Eisenstein It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, lines 29-30, "extend" should read --eXtent-- Signed and sealed this 11th day of February 1975.

(SEAL) Attest: l

C. MARSHALL DANN RUTH C. MASON Commissioner of Patents Attesting Officer and Trademarks FORM PO-IOSO 0- 9) USCOMM-DC 60376-P69 Q U. 5. GOVERNMENT PRINTING Q FFICE I)! O-QiI-Sll 

1. A regenerative heat exchanger comprising stationary structural members supporting the heat exchanger and having a hub portion, a shaft member rotatably supported in the hub portion, a cylindrical rotor concentrically fixed to the shaft member, the rotor including a plurality of sector-shaped heat exchange bundles and a support grid structure therefor, a stationary housing surrounding the rotor and means providing for the separate flow of a heating fluid and a fluid to be heated over the heat exchange bundles, each of the bundles being formed with a core of closely spaced plates including framework enclosing the core, and said framework having at least one bracket member connected to the grid structure wherein said bracket member is slotted for permitting expansion and contraction of the heat exchange bundle independent of said grid structure. 